From: Josh Berkus <josh@agliodbs.com>
To: pgsql-performance@postgresql.org
Cc: Bill Moran <wmoran@collaborativefusion.com>
Cc: Dan Harris <fbsd@drivefaster.net>
Subject: Re: Feature Request --- was: PostgreSQL Performance Tuning
Date: Fri, 27 Apr 2007 12:11:11 -0700
Message-ID: <200704271211.12439.josh@agliodbs.com> (raw)
In-Reply-To: <20070427141127.cdac56fb.wmoran@collaborativefusion.com>
References: <OFC96167D5.6BB63AC2-ON652572C9.003B5263-652572C9.003E4142@lntinfotech.com>
<46323744.5020703@drivefaster.net>
<20070427141127.cdac56fb.wmoran@collaborativefusion.com>
Bill,
> The only one that seems practical (to me) is random_page_cost. The
> others are all configuration options that I (as a DBA) want to be able
> to decide for myself.
Actually, random_page_cost *should* be a constant "4.0" or "3.5", which
represents the approximate ratio of seek/scan speed which has been
relatively constant across 6 years of HDD technology. The only reason we
make it a configuration variable is that there's defects in our cost model
which cause users to want to tinker with it.
Mind you, that's gotten better in recent versions as well. Lately I mostly
tinker with effective_cache_size and the various cpu_* stats rather than
modifying random_page_cost.
--
--Josh
Josh Berkus
PostgreSQL @ Sun
San Francisco
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To: pgsql-performance@postgresql.org
Cc: josh@agliodbs.com, wmoran@collaborativefusion.com, fbsd@drivefaster.net
Subject: Re: Feature Request --- was: PostgreSQL Performance Tuning
In-Reply-To: <200704271211.12439.josh@agliodbs.com>
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